Using Uber is not morally acceptable, a senior Labour shadow cabinet figure has said as Prime Minister Theresa May makes a keynote address on workers' rights.
Shadow business secretary Rebecca Long-Bailey accused the taxi service of "exploiting" drivers.
Ms Long-Bailey told the BBC: "I don't personally use Uber because I don't feel like it's morally acceptable, but that's not to say that they can't reform their practices.
"I don't like the way that they are exploiting their workers, and I think the recent case proved that in the courts, that suggested that the workers that were there were in fact workers, and they weren't flexible workers, and they needed to be given the adequate amount of protection and rights that workers enjoy.
"I don't want to see companies model their operation on the Uber model.
"Uber, for example, have been exploiting workers, and exploiting flexible arrangements that are in place. And it's important to have flexibility in the workplace, but it has to be two-way flexibility. It has to be flexibility that's enjoyed by the worker and the employer."
The comments came as a Government-ordered review into the employment rights of workers in the gig economy, which calls for better jobs to be created, was attacked as "feeble".
The review, headed by Matthew Taylor, a former adviser to Tony Blair, recommended a new category of worker called a "dependent contractor", and said there should be "genuine two-way flexibility", giving workers additional protections.
The report by Mr Taylor, the head of the Royal Society of Arts, said low-paid workers should not be "stuck" at the living wage minimum, nor should they face insecurity.
Speaking at its launch in London, Mrs May is expected to promise that the Government will act "to ensure that the interests of employees on traditional contracts, the self-employed and those people working in the 'gig' economy are all properly protected".
But she will insist that Britain must avoid "overbearing regulation", retain flexibility in the labour market and remain "a home to innovation, new ideas and new business models".
Unions and employment lawyers criticised the report, which has taken nine months to produce, for doing little to help the growing number of workers in delivery and taxi firms such as Deliveroo and Uber.
TUC general secretary Frances O'Grady said: "I worry that many gig economy employers will be breathing a sigh of relief this morning.
"From what we've seen, this review is not the game-changer needed to end insecurity and exploitation at work.
"We'd welcome any nuggets of good news, but it doesn't look like the report will shift the balance of power in the modern workplace."
Mr Taylor said the UK's performance on the quantity of work was strong, adding that now was the time to create better jobs.
"The review calls on the Government to adopt the ambition that all work should be fair and decent with scope for fulfilment and development.
"Despite the impact of the National Living Wage and tax credits, there will always be people who are in work but finding it hard to make ends meet.
"Our social contract with those people should include dignity at work and the realistic scope to progress in the labour market.
"Bad work - insecure, exploitative, controlling - is bad for health and wellbeing, something that generates cost for vulnerable individuals, but also for wider society.
"Improving the quality of work should be an important part of our productivity strategy," he said.
Mr Taylor set out seven "principles for fair and decent work", including a goal of "good work for all", additional protections for workers suffering unfair, one-sided flexibility, stronger incentives for firms to treat workers fairly, and a more proactive approach to workplace health.
Mrs May is expected to say that the Taylor review will inform her efforts to ensure that "the high standards of our best employers become the benchmark against which all employers are judged" and that "as the world of work changes, our practices and laws can properly reflect and accommodate those changes".
And she will add: "While avoiding overbearing regulation, we will make sure people have the rights and protections they need.
"That means building on our high employment rate and low unemployment rate - and continuing to strive for full employment.
"It means retaining the flexibility that people value, and recognising that most employers treat their staff not just fairly, but well.
"It means remaining a home to innovation, new ideas and new business models, and recognising the risks and difficulties which those striving to build their own business face - not just on day one, but every day.
"But it also means finding the right balance of rights and responsibilities, flexibilities and protections."
Unite leader Len McCluskey said the recommendations must be matched by effective enforcement of the law, adding: "Without fully resourced enforcement then all we have from Mr Taylor and the Government is a dog that is all bark and no bite."
An Uber spokesman said: "Millions of people rely on Uber to get around and tens of thousands of drivers use our app to make money on their own terms.
"Almost all taxi and private hire drivers have been self-employed for decades before our app existed and with Uber they have more control.
"Drivers are totally free to choose if, when and where they drive, with no shifts or minimum hours. In fact the main reason people say they sign up to drive with Uber is so they can be their own boss.
"Drivers using Uber made average fares of £15 per hour last year after our service fee and, even after costs, the average driver took home well over the national living wage.
"We're also proud to have moved things on from this industry's cash-in-hand past since every fare is electronically recorded, traceable and transparent."